Electric device for cutting gypsoplastic dressings



M 20, 1934. J. NIEDERHOFER 1,951,880

ELECTRIC DEVICE FOR CUTTING GYPSO-PLASTIC DRESSINGS Filed Aug. 10, 1932 Patented Mar. 20, 1934 i This-invention relates to a device-for flitting Circular saws have up gypso-plastic dressings. already been used for this purpose, but they present"the 'inconvenience that with the same 5 only straightcuts can be made. Devices are further known, which comprise a drill to be 7 first bored perpendicularly into the gypso-plastic dressing and then pushed forward-in the longitudinal direction of the dressing, exerting thus method possesses the inconvenience that the *threads of fabric,.wadding or the like, situated in or under the dressing, wind around the revolving drill and cause stopping or breaking of the same.

According to the invention these inconveniences are obviated. The cutting tool is not revolving, but consists of a chisel-like tool driven in known manner by an eccentric gear and mov- :0 ing up and. down, exerting a chisel-like effect parallel to the protecting holder for its foot :and cuts open the dressing. This chisel-like tool is of peculiar shape which will be hereinafter described. An embodiment of the cutting device according 'to the apparatus is illustrated by way of example -.in the accompanying drawing in which:-

Fig. 1 shows the same in longitudinal section, Fig. 2 in front elevation, the casing cover removed. e

Fig. 3 shows the chisel with foot in side elevatlon on enlarged scale.

s Figure 4 is an elevational view of the chisel-like foot.

I Figs. 4a, 4b and 40. show cross sections through the chisel-like tool on lines A-A, BB and I.CC of Fig. 4.

The driving mechanism for the cutting device consists of a generally known eccentric gear. In the form of construction illustrated a shaft 3 running in ball bearings 4 is journalled in a handle :1 and serves for driving the eccentric gear5. This I gear is accommodated in a casing 6 and consists of the eccentric proper 5 acting upon aroller 7- mounted in balls and rolling in an eccentric ring 8, which has aboveand below slidablepieces 9 and 10. The chisel 13 is inserted in the lower slidable piece 10. Guide bars 11 and 12 serve to facilitate the guiding of said slidable pieces 10. Theeccentric gear is driven by a "flexible shaft 15'coming from any suitable engine) A "clutch .2 is provided between shaft 3 and the flexible shaft 15. e I The characteristicfeatureof the invention is not the eccentric gear but the peculiar shape a cutting effect similar to a milling cutter. This and backward direction. Also the rear side of ELnoTmd-ImvIoE roR CUTTINGfGYPSO PLASTIQ-DRESVSINGS i e .i Johanni Niederhefer, German iii: 'T 1 T ApplicationAugusta-10;1932; Serial No.- 628,159 j 1.:

i -In G ermany December 12, 1931i 7 v v I v ",j W el 'i'ins. (c1...12'ii-i-s zjj i of the cuttin'g'tool whichjisfcalled chisel owing toits chiselglik'e' acme; l ,jThis chisel 13 is. com: po'sedof three portions ofdifferent thickness} The first portion 13a is short 'and' saw-like 'so that it serves for ripping the gypso-plastic dressing. The next following portion in upward direction is a slightly longer but thinner saw-like piece 13b, the thickness of which corresponds to the width of the foot holder of the chisel. The third part 130 in upward direction is a drill-like piece, the edges of the drills being serrated for the purpose to eject the chips. This third part 13c of the chisel is thicker than the saw blade-like parts in order that the chips can be easily ejected, the

out being enlarged at the same time. This third 7 part 130 is tapered from upwards to below and therefore takes up chips ejected by the saw-like parts 13a and 13b and conveys them towards the outer side. The chisel, in order to render it stable against the cutting pressure, has reinforcslidable piece 10 (Figs. 1 and 2). The chisel 13 acts upon the foot '16 designed to be pushed under the dressing and terminating at the top end in an edge 16a, which continues along the foot holder 16b; whereas the cutting edge on the foot 16 serves to make incisions in the dressing from below, the cutting edges along the foot holder 16b serve for more easily guiding the foot in forward the foot holder, 16b has a cutting edge. The foot holder is'fixed'by a plate v1'7 standing at right angles (Figs. 1 and 2) on the casing 6. The foot 16 carries in its-lower side an insulating plate foot is pushed under the gypso-plastic dressing comprising a chiselcomposed of three parts, the

lowermost part being of a certain thickness and saw-like, the next higher part being also sawlike but thinner and longer than the lowermost part and the uppermost part being drill-like, the

drill edges being serrated, the uppermost part tapering from above downwards.

'2. Cutting device for gypso-plastic dressing comprising in combination a casing, an eccentric gear insaidcasing-a chisel projectingfrom said casing and adapted .to be moved vertically up 75 ing ribs 14, a nose 14a of which bears against the I and down by said eccentric gear, a foot ior said cutter, a cutting edge extending along the upper end of said foot and from there along the foot holder, and'a right angular plate connecting said foot holder with said casing of the eccentric gear.

3. Cutting, device ator gypso plastic dressing comprising .in' combination a casing, an eccentric gear in said casing, a chisel projecting from said casing and adapted to be moved vertically up and; v

= of said eccentric gear, an eccentric'ring surround- 'ing said roller, and

down by said eccentric gear, a foot for said outter, a cutting edge extending along the upper end 01' said foot and from there along the foot holder a d also a cutting edge on therear side of said toot'holder, and a right angular plate connecting said foot holder with said casing of the eccentric'gear. n 4. Cutting device for gypso-plastic dressing comprising in combination, a casing, an eccentric gear in said casing, a chiselprojecting from said casing and adaptedto be moved vertically up and down by said eccentric gear, a foot for said cutter, a" cutting 'edge extending, along, the upper end of said foot and from there along the foot holder, a'right angular plate connecting said-mot holder with said casing of the eccentric gear,'- and an insulating foot plate, for instance of ivory, in said foot. v v

' 5. Cutting device comprisingin combination a gear casing," an ec-\ centric gear in said for id reasingfi's,

gear casing, a horizontalha'n dle in which said gear casing is mounted, a roller slidable elements running on rollers supported by said eccentric ring.

g 6, Cutting device for gypso-plastic dressings, 3

comprising in'combination a gear casing, an eccentric gear in said gear casing, a horizontal hanndle inwhich said gear casing is mounted, a roller of said eccentric gear, an eccentric ring sur- I rounding said roller, slidable elements running on roller-sf supported by said eccentric ring, and. guidebars for saidslidable-elements. r 1 I JOHANN nmnnarror'nn 

